Stamp



FIG. 1 is a perspective view of a stamp, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof; and,

FIG. 6 is a top view thereof. 

The ornamental design for a stamp, as shown and described. 